JPH04127939A - Method and apparatus for producing rapidly cooled metal strip - Google Patents

Abstract

PURPOSE:To prevent an adverse influence on the characteristic of a metal strip due to a splashed and involved molten metal particles developed at the time of starting pouring of the molten metal into a paddle by arranging a trap for sticking the splashed particles of molten metal at the position opposite to the progressing direction of the metal strip just below the nozzle and just near the nozzle. CONSTITUTION:The trap 5 is one for absorbing the molten metal splashes 4 just after injecting and is set at just near the nozzle in rear part of the nozzle 1. At the time of analyzing it by picking up the scene that the molten metal splash 4 is splashed from the nozzle 1 backward with a video camera, the molten metal splash is always splashed backward in the shape of slipping the splash on the surface of a roll 3. Therefore, fitting height of the trap 5 may be near the surface of roll 3 and practically, there is no problem, even if this is brought into contact with the surface of roll. The material having m.p. higher than temp. of the molten metal splash is used as the, quality of the trap 5, and by using metal fiber, metal pipe and metal plate, sticking reliability of the molten metal can be drastically improved. Sticking part of the trap 5 is heated with a heating device 6.

Description

Detailed Description of the Invention <Industrial Field of Application> The present invention relates to a method for producing a thin metal ribbon by rapidly cooling and solidifying a molten metal, and relates to a method for producing a thin metal ribbon by rapidly cooling and solidifying a molten metal. The present invention relates to a method and apparatus that make it possible to continuously produce wide ribbons by removing grains.

<Prior Art> In the production of a rapidly cooled metal ribbon, molten metal is rapidly solidified on the surface of a cooling roll rotating at high speed, and is continuously formed into a ribbon. In particular, when manufacturing an amorphous ribbon with a thickness of about 301 Im, the gap between the nozzle and the cooling roll is 100 to 500 mm.
It is carried out in a narrow gap of about pm. The properties of the ribbon produced in such a narrow gap will be significantly impaired unless the pool (hereinafter referred to as paddle) formed between the nozzle and the roll is stabilized. Particularly when starting pouring for the first time, if molten steel droplets (droplets) scattered by molten steel injection adhere to the nozzle or are drawn into the paddle part again on the roll surface, the paddle will be partially disturbed and the Scratches will be left on the ribbon surface from the beginning to the end of the board.

In order to solve this problem, Japanese Patent Application Laid-Open No. 61-296941 proposes to provide a flow velocity control plate inside a horizontally injecting nozzle to make the flow of molten steel uniform. This method is based on the assumption that hot water is passed through a channel with a circular cross-section from a tandy tube to a nozzle with a different cross-section, and the non-uniformity of the flow rate of hot water caused by discontinuities in the cross-section is eliminated. It's a problem. Therefore, when using a nozzle with uniform convergence in the vertical direction, it is not necessarily possible to prevent the generation of droplet flow using this method.

Further, Japanese Patent Laid-Open No. 63-16142 also proposes the use of a plurality of flow velocity control plates in a similar method. However, for the reasons mentioned above, this method cannot be directly applied to the flow of hot water flowing down in the vertical direction. In addition, since all of these methods attach the control plate inside the nozzle, they require adhesiveness between the nozzle and the control plate and measures to prevent the nozzle from cracking during heating, which requires strict process control and yield. This has the disadvantage of causing a decline.

The present inventors propose a means for solving the problem of initial molten steel splash particles, using an idea completely different from such a control method. That is, the present invention provides a method for easily and highly accurately removing the molten metal splash particles that are initially generated, regardless of the width of the nozzle, the molten steel injection pressure (molten @ flow rate), and the physical property values of molten steel. , we propose a device that can be suitably used for this purpose.

<Problems to be Solved by the Invention> The present invention solves problems that occur at the start of pouring when molten metal is injected onto the surface of a rotating cooling roll through a slit nozzle and rapidly solidified to cast a rapidly solidified metal ribbon. This prevents molten steel splash particles from being caught up in the paddle and adversely affecting the properties of the metal ribbon.

In other words, the present invention prevents the molten metal from hitting the roll and causing the molten steel droplets to become unstable at the start of injection when the molten metal rapidly solidifies and is drawn into the paddle formed immediately after injection, and from causing the nozzle injection to become unstable. This solves the problem of molten steel adhering to the vicinity of holes and making the flow of molten steel uneven.

Means for Solving the Problems Most of the conventional solutions to the problem of molten steel splashing have been related to controlling the flow of molten steel.

However, according to the findings of the present inventors, in industrially produced wide-width nozzles, for example, nozzles with a ribbon width of over 100 m, an undisturbed and smooth surface is emitted from the injection hole corresponding to the ribbon width. It turned out that it is extremely difficult to create a uniform flow. Also, even if you create a uniform flow of molten steel in the nozzle, what happens? 8 When the steel first comes into contact with the roll, it may partially pop or not get wet enough on the roll due to the influence of minute moisture composition or dust in the atmosphere that clings to the roll surface. It turns out that droplets are generated. For these reasons, even if only the flow of molten steel in the nozzle is solved, it is not possible to completely prevent splashing.

Furthermore, since the nozzle for manufacturing quenched ribbons has a thin nozzle injection hole of less than 1 mm, it becomes difficult to create a uniform flow when the nozzle width increases. The occurrence of molten steel splash at the start of pouring, which cannot be expected to improve, occurs within 1 second under pouring conditions with a proper nozzle-roll gap and mass balance, and a stable puddle is maintained thereafter. I found out that it was. Therefore, if the molten steel splash can be disposed of within this time, there will be no problem.

The present inventors developed a technology to remove t8g droplets that are generated within 1 second at the beginning of pouring, and found a solution from a completely different perspective from conventional pouring control techniques.

That is, the present invention provides: (1) a single-roll rapidly cooled metal ribbon production method in which molten metal is injected onto the surface of a rotating cooling roll through a slit-shaped nozzle, and is solidified to form a cold metal ribbon; A method of casting a cold metal ribbon characterized in that droplets of molten metal that are scattered in the opposite direction to the traveling direction of the metal ribbon immediately below the nozzle are removed during the scattering during the initial stage of pouring from the nozzle. (2) The molten metal splash particles are removed by arranging a trap directly under the nozzle on the opposite side to the metal ribbon traveling direction and at a position immediately adjacent to the nozzle. A method for manufacturing a cold metal ribbon according to claim (1), characterized in that casting is carried out while removing the cold metal ribbon by adhering to the trap and removing the cold metal ribbon. In a single-roll rapidly cooled metal ribbon manufacturing device that injects molten metal and cools it to solidify it to obtain a two-cooled metal ribbon, on the opposite side to the direction in which the metal ribbon travels directly under the nozzle,
and a quenched metal ribbon manufacturing apparatus, characterized in that a trap is disposed in the immediate vicinity of the nozzle to which droplets of molten metal adhere. An apparatus for producing a quenched metal ribbon according to (3), which is a metal member having a melting point higher than the temperature.

FIG. 1 shows an example of the structure of the present invention. Molten metal 2 injected from a nozzle 1 hits the surface of a roll 3 rotating directly below the nozzle injection hole, and is rapidly solidified. However, immediately after injection, molten metal droplets 4 fly in a direction opposite to the direction in which the ribbon travels (hereinafter referred to as "backward") as shown in FIG. 2a for the reason detailed above.

If casting is performed without removing these droplets 4 during scattering, then the molten metal droplets 4 will be molten or solidified on the surface of the roll 3 and will be transferred to the nozzle again, as shown in Figure 2. 1 and reaches the injection hole of the nozzle 1 as shown in FIG. 2C. As a result, the paddle is disturbed and defects such as streaks and holes are generated on the surface of the ribbon at locations affected by the molten metal splash 4, and in severe cases, the nozzle 1
Droplets are attached to the bottom of the container in the direction of travel to generate unsolidified portions.

The trap 5 shown in FIG. 1 is for adsorbing the molten metal droplets 4 immediately after injection, and is arranged immediately behind the nozzle l. When the molten metal droplets 4 flying backward from the nozzle 1 were recorded with a video camera and analyzed, it was found that the molten metal droplets always flew backwards while sliding on the surface of the roll 1. Therefore, the trap 5 may be attached at a height close to the surface of the roll 1, and there is no problem even if it substantially contacts the roll surface.

It was also found that the flight distance of molten metal droplets varied depending on the size of the droplets and the condition of the roll surface.

In order to reliably weld the droplets in such a state, it is necessary to arrange the trap 5 immediately behind the nozzle.

The material used for the droplet welding part of the trap 5 needs to have a melting point higher than the temperature of the molten metal.

For example, the inventors have found that the temperature of molten steel is 3% at 1550°C.
When producing a ribbon of Si-containing iron alloy, amorphous alloy fibers with a melting point of about 1200°C were bundled and used in the molten steel welding part of trap 5, but the amorphous alloy fibers were melted by splashes and had no effect. . Also,
Similar results were obtained when a thin copper wire was used to manufacture a ribbon of an amorphous alloy with a molten steel temperature of 1320°C. On the contrary, in all 28 cases where a material with a higher melting point than the molten steel was used, molten steel could be welded without melting.

For the above reasons, it was found that the material of the trap 5 needs to be a material with a melting point higher than the temperature of the molten metal droplets. It is also limited to a high range.

When trap 5 is made of ceramics such as BN, silicon nitride, fused silica, or organic polymer materials, the welding of droplets is extremely unstable, and sometimes damage can occur due to breakage or burnout, resulting in a negative effect. In contrast, when metal fibers, metal pipes, and metal plates are used, the accuracy of adhesion of molten steel can be significantly improved.

However, even if the welded part is metal, when the temperature difference between the molten metal droplets and the welded part is large, the droplets often come off the welded part. In order to prevent this, the welded part of the trap 5 was heated by the heating device 6, and it was found that there was a range where the droplets were completely welded. Table 1 shows the weld side joints when the welded part was heated and when it was not heated. From Table 1, it can be clearly seen that heating the welded portion allows for more reliable welding. Although the heating temperature of the welded portion at this time varies somewhat depending on the type, size, and shape of the metal, it has been found that in most cases, a temperature of 250° C. or higher is sufficient to achieve sufficient welding. The reason why it is necessary to heat the welded part is not clear, but it is speculated that it is probably due to the familiarity of the droplets to the metal and the activation state of the metal surface.

Table 1 <Example> Using a nozzle with an injection hole width of 150 mm and a thickness of 0.7 mm, molten steel of Fe-B-5t eutectic composition was injected into a copper roll at 1320''C. In the opposite direction, a nichrome wire was heated to 1) 00°C and placed parallel to the nozzle injection hole.

During the initial 0.6 seconds of injection, the diameter 2 from near the center of the nozzle width
Three 4-meter splashes flew backwards, but none of them adhered to the nichrome wire and were not pulled back into the nozzle injection hole. The attached splash was welded to the nichrome wire in a wet state.

<Effects of the Invention> As explained above, according to the present invention, by quickly solving the initial troubles in manufacturing cold ribbon using a simple and reliable method, continuous production of thin ribbon can be made possible. Because it can be done, the effect is extremely large.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the structure of the present invention, and FIG. 2 is an explanatory diagram showing the trajectory of molten metal splash particles. DESCRIPTION OF SYMBOLS 1... Nozzle, 2... Molten steel, 3... Roll, 4... Molten metal splash particles, 5... Trap, 6... Heating device.

Claims (4)

[Claims] (1) In a single-roll quenched metal ribbon manufacturing method in which molten metal is injected onto the surface of a rotating cooling roll through a slit-shaped nozzle and rapidly solidified to cast a quenched metal ribbon,
A method for producing a quenched metal ribbon, characterized by casting while removing droplets of molten metal that are scattered in the opposite direction to the direction of movement of the metal ribbon immediately below the nozzle at the beginning of pouring from a nozzle. . (2) The removal of molten metal splash particles is achieved by arranging a trap directly below the nozzle on the opposite side to the direction of movement of the metal ribbon and at a position immediately adjacent to the nozzle, and removing the flying molten metal splash particles into the trap. 2. The method for producing a rapidly solidified metal ribbon according to claim 1, wherein casting is performed while adhering to and removing the metal ribbon. (3) In a single-roll type rapidly solidified metal ribbon manufacturing device that injects molten metal onto the surface of a rotating cooling roll through a slit-shaped nozzle and rapidly solidifies it to obtain a rapidly solidified metal ribbon, the metal ribbon progresses directly below the nozzle. 1. An apparatus for producing rapidly cooled metal ribbon, characterized in that a trap is disposed on the opposite side of the direction and in a position immediately adjacent to a nozzle to which droplets of molten metal are attached. (4) The apparatus for producing a quenched metal ribbon according to claim 3, wherein the trap is a metal member having a melting point higher than the temperature of the molten metal to be cast.